If you thought your everyday average stapler was capable of one thing and one thing only, you were right, but there's a little secret hidden within the metallic depths that few know about. You never know when you may need to extend the width of your staples, or even why, but that fact is that you can, and it all lies in an unassuming little piece of the steel on the bottom.

There's a little metal plate on the bottom of your stapler, and what do you know! It moves, and can seemingly control the width of your staples.

Source: Wimp

This video by Sarah Barlow better explains how this nifty little trick works.